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United States Patent | 5,689,819 |
Nishimura ,   et al. | November 18, 1997 |
In a transmitter-receiver having a transmitting circuit and a receiving circuit, the present invention mitigates an interference between the transmitting circuit and the receiving circuit. A quartz-crystal oscillator is provided as a common reference signal source for the local oscillators and the relation among frequencies is determined so that the frequencies such as local oscillating frequencies and intermediate frequencies within the transmitter-receiver do not overlap each other. Interferences between the transmitting circuit and the receiving circuit are mitigated to prevent a characteristic deterioration, spurious radiation, etc. Thereby the transmitter-receiver may be reduced in size and weight. Further, by sharing a quartz-crystal oscillator having a high frequency stability, narrowing of bands in radio channel spacing may be readily achieved.
Inventors: | Nishimura; Shuji (Tokyo, JP); Itoh; Kenji (Tokyo, JP) |
Assignee: | Mitsubishi Denki Kabushiki Kaisha (JP) |
Appl. No.: | 562066 |
Filed: | November 22, 1995 |
Jun 05, 1995[JP] | 7-137998 |
Current U.S. Class: | 455/86; 455/78 |
Intern'l Class: | H04B 001/40 |
Field of Search: | 455/78,79,82,83,84,85,86,87,310 |
2903693 | Jan., 1959 | Ley | 455/78. |
4373205 | Feb., 1983 | Mizota. | |
5123008 | Jun., 1992 | Beesley | 455/86. |
5276915 | Jan., 1994 | Marko et al. | 455/86. |
5307378 | Apr., 1994 | Norimatsu | 455/87. |
5471652 | Nov., 1995 | Hulkko | 455/76. |
5483679 | Jan., 1996 | Sasaki | 455/86. |
Foreign Patent Documents | |||
0246658 | Nov., 1987 | EP. | |
4-133508 | May., 1992 | JP. | |
93/16530 | Aug., 1993 | WO. | |
96/05661 | Feb., 1996 | WO. |